If you talked in class he sometimes demonstrated the famous 'Tangent' which meant that he told you to bend over and sliced a ruler edge downwards on your bottom - it was extremely painful and few people dared to talk in class after witnessing this

Ayone remember this?

Once he caught B------- singing to himself and made the mortified boy stand on a stool and sing the whole of a nursery rhyme through his tears

I rarely felt sorrier for a lad - it seemed crueller in it's humiliation than the simple pain of a tangent.